The human heart comprises four heart valves. Two of these valves are located between the left and right atria and ventricles and are called the mitral and tricuspid valves, respectively. These valves serve to maintain one-way blood flow into the ventricles and to prevent the regurgitation of blood back into the atria. Although the present invention can be used for many different applications including mitral and tricuspid valve repair, for the purposes of example it will hereinafter be described in connection with the repair of a mitral valve.
Mitral valve repair is the surgical procedure of choice to correct mitral regurgitation of all etiologies. With the use of current surgical techniques, approximately 70 to 95% of all regurgitant mitral valves can be repaired. The advantages of mitral valve repair over mitral valve replacement are well documented. These advantages include better preservation of cardiac function and reduced risk of anticoagulant-related hemorrhage, thromboembolism and endocarditis.
Nearly all mitral valve repairs include an annuloplasty. The annuloplasty consists of implanting a prosthetic band or ring that surrounds all or part of the circumference of the annulus of the valve. The annuloplasty serves several functions: it remodels the annulus, decreases tension on suture lines, increases leaflet coaptation, and prevents recurrent annular dilation. In addition, the annuloplasty improves repair durability.
The placement of a prosthetic annuloplasty band or ring in the heart results in a risk of thromboembolism and infection; these risks are unavoidable and persist for the life of the patient. Formation of blood clots on prosthetic materials in the heart often results in stroke, and infection of a prosthetic annuloplasty band or ring may lead to life-threatening sepsis and the need for urgent re-operation.
The ideal annuloplasty would be effected using a universally flexible, autologous material. Such a material does in fact exist, in the form of the patient's own pericardium. The pericardium is the sac in which the heart sits. The pericardium is often used by heart surgeons to repair congenital heart defects. It heals well, and almost never becomes infected. However, the pericardium can be difficult to work with.
In order to make practical use of autologous pericardium for a mitral valve annuloplasty, the surgeon would need apparatus to facilitate the creation of a tissue annuloplasty band or ring of the appropriate length and thickness, and to ensure that the tissue annuloplasty band or ring will maintain the chosen dimensions while it is applied to the heart.
The development of a system for constructing and deploying a pericardial annuloplasty band or ring would have great benefit for the patient. No prosthetic material would be placed in the heart, greatly reducing the risk of thromboembolism and infection. No anticoagulation would be necessary. In addition, pericardium remains flexible as it heals, and this would result in preserved mitral valve physiology.